The present invention pertains generally to fire fighting, and more particularly to an imaging system and method which allows fire fighting personnel to clearly view objects in a smoke and fire filled fire environment.
Smoke and fire make it difficult and sometimes impossible for fire fighting personnel to view a fire scene. As such, living victims can be overlooked, and dangerous surroundings such as obstructions, weakened structures, open floors, and stairs can present an extreme personnel hazard. The present invention comprises an imaging system that allows fire-fighting personnel to view images through the smoke and fire.
There are several drawbacks to even the most modem and sophisticated of thermal imaging systems. First and foremost is that the intense heat from a fire obscures any thermal signature that may be behind the flame front. Thus a baby or another firefighter may not be saved because the firefighter scanning the room didn""t see them. Second is that objects without a thermal signature such as downed electrical cables or fallen/damaged structural elements are virtually invisible and thus may easily be overlooked by the firefighter hurrying to save someone""s life. Finally, the detected 8,000 to 14,000 nanometer radiation does not penetrate through glass or water. For this reason a thermal imaging system cannot be used remotely from outside of the building or structure. Additionally, the thermal bloom from a fire renders thermal imaging systems virtually useless for objects behind the flames. Furthermore, these systems cannot see through glass or water and only allow the firefighter to see objects with a thermal signature such as the fire and the victim but all other obstacles or impediments that may cause the firefighter to be injured are not visible at all.
Combined LIDAR and RADAR technology is known in the art. For example, U.S. Pat. No. 5,822,047 is directed to a modulated LIDAR system, in which a laser for generating an optical carrier signal and a microwave generator for generating a coded microwave signal are provided. A modulator is further provided for modulating the carrier signal with the microwave signal, whereby a modulated signal is generated. A method of detecting a reflective surface is also disclosed, in which an optical carrier signal is generated, the carrier signal is modulated with a coded microwave signal, the modulated signal is reflected off of a reflective surface and the reflected signal is recovered.
The present invention comprises a man-portable, affordable, eye-safe imaging system which permits not only the visualization of victims, but also aspects of their surroundings (steps, obstructions, missing floors, fallen objects in path, etc) that are obscured by the glare and thermal bloom of the fire and the scattering of light by the smoke.
The system can be individually carried or mounted on a deployment vehicle (boom, ladder, or robot) and sent into the incident area where the display shows architectural features (stairs, walls, doorways, missing stairs), objects (furniture, fallen items), and persons (other emergency personnel, victims, pets). The system can also be used through a window from outside of a building or structure.
This system can also be used remotely from outside of the building or structure and will be used in conjunction with exiting thermal imaging systems to provide the firefighter with a much better understanding of the situation at hand. Additionally, military applications of the present invention include visualization of targets through flame and smoke obscured battlefields as well as fire fighting of vehicular and aircraft fires.
In accordance with a preferred embodiment of the invention, an imaging system for viewing objects at a fire scene includes a near-IR laser for generating a beam of light that may be directed at the fire scene. A microwave source modulates the laser output with a reference microwave signal, thereby resulting in an amplitude-modulated beam of light. An optical detector receives reflected light from the fire scene and generates a received microwave signal. A filter is disposed between the optical detector and the fire scene to remove unwanted signals. The output of the optical detector is routed to a microwave receiver. The microwave receiver xe2x80x9cbeatsxe2x80x9d the received microwave signal from the optical detector with the reference microwave signal in a xe2x80x9chomodynexe2x80x9d process, thereby producing a composite microwave signal that is routed to a dispay.
In accordance with an aspect of the invention, the laser generates light having a wave length of between 1,400 nanometers and 1,600 nanometers.
In accordance with another aspect of the invention, the beam of light has a width of about 20xc2x0 to 30xc2x0.
In accordance with another aspect of the invention, the reference microwave signal has a frequency of between 10 megahertz and 5 gigahertz.
In accordance with another aspect of the invention, a frequency control provides for selectively varying the frequency of the reference microwave signal.
In accordance with another aspect of the invention, the frequency control is automatic and scans a band of microwave frequencies to arrive at an optimal fire scene display.
In accordance with another aspect of the invention, the filter has a width of xc2x10.05 nanometers.
In accordance with another preferred embodiment of the invention, an imaging system for viewing objects at a fire scene includes a laser for generating a beam of light that may be directed at the fire scene. A pulse generator generates a reference pulse that is used to trigger the laser thereby producing a pulsed beam of light. A delay generator is connected to the pulse generator and produces a delayed pulse. A gated optical detector receives reflected light from the fire scene through a filter. The gated optical detector also receives the delayed pulse from the delay generator, and produces a gated output, wherein the gated output contains reflections from a distance corresponding to the delayed pulse. A display displays the gated output.
In accordance with an aspect of the invention, the reference pulse has a pulse width of between about 1 and 3 nanoseconds.
In accordance with another aspect of the invention, a delay control is provided for selectively varying the time relationship between the reference pulse and the delayed pulse.
Other aspects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.